This invention relates to pneumatic control systems and relates more particularly to pneumatic starters for use in starting aircraft engines.
Typically a pneumatic starter of the class referred to includes a fixed level oil sump and normally operates for a short duty cycle while starting the engine of an aircraft. In the instance of system malfunction the starter many times operates undetected after engine starting and is subject to overspeeding and overheating. This typically results in severe internal damage to the starter and often times causes secondary damage to associated components.
A continuing problem for such a system has been in detecting the system malfunction which can ultimately cause starter overspeeding and destruction. Problems of detection of this event are compounded by the relatively short duty cycle of the starter, its small torque drag on a large aircraft engine, and relatively inconsequential effect on engine performance prior to damage to secondary components. Usually the occurrence of such a malfunction is first noted after severe damge to the starter.
Accordingly it will be apparent that there exists a need for a mechanism and method for sensing malfunction in a timely fashion to permit preventive measures to be taken prior to starter destruction. While prior art systems such as illustrated in U.S. Pat. Nos. 1,248,143; 1,600,322; 1,712,116; 1,783,395; 2,707,864; 2,741,085; 3,008,688; 3,338,255; and 3,817,353, have certain similarities with the present invention, none of these prior art systems recognize the discoveries associated with the present invention nor the attendant results in specific structure and method thereof.